Mechanics and Dynamics of Viscoelastic Metacomposites

超材料是一种微结构材料，具有不寻常的特性，如负的表观刚度和密度，通常不被观察到。这些特殊的性能使得传统材料无法实现的结构性能得以实现。一种这样的可能性是抑制或显著地阻尼结构内某些频率的波的传播。该项目研究了实现超复合材料的可能性，这种材料可以通过调整材料的微观结构和部件的性能来抑制或显著降低振动、冲击和爆炸载荷。如果实现，这种新颖而不寻常的材料的创新将为民用基础设施提供非常有效的保护系统，防止爆炸、撞击和地震等危害。这项研究的直接变革影响的其他领域是机械系统的振动控制，能量收集和传感。PI将每年为高中学生和教师举办讲习班，向他们介绍基于模拟的工程概念。该研究将阐明声超复合材料组分的粘弹性随时间变化特性、微观结构形态及其在动载下的减波特性之间的基本关系。对于不表现出弹性响应的超材料，目前缺乏这种基本的结构-性质关系。本项目的主要假设是，利用材料非均质性引起的波色散和材料黏性引起的波耗散的相互作用机制，可以控制和抑制波在大频段内的传播。（可调带隙）。本研究将发展一种高效、准确的非均质材料非线性瞬态动力响应的多尺度均匀化计算方法，并对粘弹性超复合材料的波传播和能量耗散特性进行全面研究。渐近分析和数学均匀化技术将用于制定高阶平衡方程，可以准确地捕捉非线性色散。计算解决算法将被开发，以准确地捕捉在多维微结构带隙的出现。这些计算工具和算法将用于定制复合材料的形态组成，以在目标频率范围内实现优越的波缓解性能。研究的重点是具有耗散、粘弹性组分的核-壳颗粒增强复合材料。

Metamaterials are microachitectured materials that exhibit unusual properties, such as negative apparent stiffness and density, not ordinarily observed. These exceptional properties allow realization of structural behavior that is not possible with conventional materials. One such possibility is suppressing or significantly damping the propagation of waves of certain of frequencies within a structure. This project investigates the possibility of realizing metacomposite materials that can suppress or significantly damp vibration, impact and blast loads by tuning the material microstructure and properties of its components. If realized, the innovation of this novel and unusual class of materials will result in very effective protection systems for civil infrastructure against hazards such as blast, impact and earthquakes. Additional areas of direct transformative impact of this research are vibration control of mechanical systems, energy harvesting and sensing. The PI will hold annual workshops for high school students and teachers to introduce them to the concept of simulation-based engineering. The research will elucidate the fundamental relationships between time dependent viscoelastic properties of the constituents of acoustic metacomposite materials, its microstructural morphology and its wave mitigation characteristics under dynamic loading. This fundamental structure-property relationship is currently lacking for metamaterials that do not exhibit elastic response. The primary hypothesis of this project is that the interacting mechanisms of wave dispersion induced by the material heterogeneity and wave dissipation due to material viscosity can be employed to control and suppress wave propagation within large frequency bands(i.e., tunable bandgaps). Within this research, an efficient and accurate multiscale computational homogenization methodology for transient dynamic response of heterogeneous materials with material nonlinearity will be developed, and a comprehensive study on wave propagation and energy dissipation characteristics of viscoelastic metacomposites will be performed. Asymptotic analysis and the mathematical homogenization techniques will be used to formulate high order balance equations that can accurately capture nonlinear dispersion. Computational solution algorithms will be developed to accurately capture the emergence of bandgaps in multidimensional microstructures. These computational tools and algorithms will be employed to tailor the morphological makeup of a composite material for achieving superior wave mitigation property at targeted frequency ranges. The focus of the investigations is on core-shell particle-reinforced composites with dissipative,viscoelastic, constituents.